1. Field of the Invention
This invention relates to apparatus for folding the closure flap of envelopes and, more particularly, to apparatus for folding the closure flap of an envelope that includes a rotatable receiver having a plurality of envelope receiving radial slots therein.
2. Description of the Prior Art
In the past, envelope closure flaps have been folded be several different types of folding devices. For example, the envelope closure flap was folded by means of a reciprocating blade that engaged the score line of the closure flap and fed the partially folded closure flap between a pair of pressure rollers. The pressure rolls completed the folding of the closure flap against the body of the envelope. This type of folding device was slow and not suited for present day high speed envelope making machines.
As an improvement over the reciprocating blade type folding device, the so-called "upset folding" devices were developed. The "upset folding" device conveys the envelope into a trap having a stop device that stops the envelope blank when the closure flap score line is positioned between a pair of pressure roll. The pressure rolls engage the envelope along the closure flap score line and fold the closure flap over the envelope body. This type of closure flap folding device also limits the speed of the envelope making machine because the envelope is conveyed into a trap against a stop device and the envelope must stop and reverse direction. Also, the envelopes frequently fill with air during the folding operation and cause jams and machine malfunctions.
To eliminate the problem of collecting air in the envelope while the closure flap is being folded, rotary type closure flap folding devices, such as that illustrated in U.S. Pat. No. 3,668,982, were developed. The roll-type closure flap folding devices require suction devices to maintain the envelopes on the rolls and further are limited by the small number of envelopes that can be positioned on the closure flap roll at one time. This arrangement also limits the output rate of the envelope making machine.
There is a need for a relatively simple device for folding the envelope closure flaps at a high speed without collecting air in the envelopes during the folding of the closure flap.